Magnetic etch stop layer for spin-transfer torque magnetoresistive random access memory magnetic tunnel junction device

ABSTRACT

An apparatus includes a capping layer disposed on top of a free layer. The apparatus also includes a magnetic etch stop layer disposed on top of the capping layer. The capping layer and the magnetic etch stop layer are included in a spin-transfer torque magnetoresistive random access memory (STT-MRAM) magnetic tunnel junction (MTJ) device.

I. FIELD

The present disclosure is generally related to a magnetic etch stoplayer for a spin-transfer torque magnetoresistive random access memory(STT-MRAM) magnetic tunnel junction (MTJ) device.

II. DESCRIPTION OF RELATED ART

Advances in technology have resulted in smaller and more powerfulcomputing devices. For example, there currently exist a variety ofportable personal computing devices, including wireless telephones suchas mobile and smart phones, tablets, and laptop computers that aresmall, lightweight, and easily carried by users. These devices cancommunicate voice and data packets over wireless networks. Further, manysuch devices incorporate additional functionality such as a digitalstill camera, a digital video camera, a digital recorder, and an audiofile player. Also, such devices can process executable instructions,including software applications, such as a web browser application, thatcan be used to access the Internet. As such, these devices can includesignificant computing capabilities.

Wireless telephones may include spin-transfer torque magnetoresistiverandom access memory (STT-MRAM) devices to store data. STT-MRAM devicesmay be implemented using a magnetic tunnel junction (MTJ) device tostore data. For example, an MTJ device may include a free layer (e.g., astorage layer) having a magnetic moment representative of a data value.During fabrication, magnetic properties of the free layer may be damagedduring etching of adjacent layers (e.g., during etching of a cappinglayer). Sacrificial etch stop layers (or buffer layers) may be depositedon top of the capping layer to protect the free layer during etching toreduce degradation; however, significant degradation may occurregardless of the deposition of the sacrificial etch stop layers.

III. SUMMARY

Techniques for protecting a free layer of a spin-transfer torquemagnetoresistive random access memory (STT-MRAM) magnetic tunneljunction (MTJ) device are shown. The MTJ device may include pinnedlayers, a tunneling barrier layer, the free layer, a capping layer, amagnetic etch stop layer, and a top electrode. In a particularembodiment, the MTJ device may be a perpendicular MTJ device. Forexample, the magnetic moment of the free layer and the magnetic momentof one or more layers in the pinned layers may be perpendicular to theplane of the free layer.

The capping layer above the free layer may be comprised of MagnesiumOxide (MgO), Aluminum Oxide (AlOx), Hafnium Oxide (HfOx), or TantalumOxide (TaOx) and the magnetic etch stop layer may be comprised of CobaltIron Boron (CoFeB), Cobalt Iron (CoFe), Iron Boron (FeB), Cobalt Iron(CoFe), Nickel Iron Boron (NiFeB), Nickel Iron Silicon Boron (NiFeSiB),or Nickel Iron (NiFe). The magnetic etch stop layer may be deposited ontop of the capping layer to protect both layers during etching. Forexample, a hard mask may be placed on the top electrode (located on topof the magnetic etch stop layer), and the MTJ device may undergo anetching process. During the etching process, the magnetic etch stoplayer (in addition to the capping layer) may protect magnetic propertiesof the free layer. For example, the magnetic etch stop layer maystabilize the perpendicular magnetic anisotropy of the free layer duringhigh annealing temperatures associated with an etching process (e.g., areactive ion etching process). In a first embodiment, the magnetic etchstop layer may be sufficiently thin (e.g., approximately 5 Angstromsthick or less) to be substantially magnetically inert (i.e.,“magnetically dead”). In a second embodiment, the magnetic etch stoplayer may be thicker (e.g., approximately between 10 Angstroms and 30Angstroms) to exhibit a magnetic moment.

In a particular embodiment, an apparatus includes a capping layerdisposed on top of a free layer. The apparatus also includes a magneticetch stop layer disposed on top of the capping layer. The capping layerand the magnetic etch stop layer are included in a spin-transfer torquemagnetoresistive random access memory (STT-MRAM) magnetic tunneljunction (MTJ) device.

In another particular embodiment, a method of forming a spin-transfertorque magnetoresistive random access memory (STT-MRAM) magnetic tunneljunction (MTJ) device includes depositing a capping layer on top of afree layer. The method also includes depositing a magnetic etch stoplayer on top of the capping layer.

In another particular embodiment, an apparatus includes first means forprotecting a free layer disposed on top of the free layer. The apparatusalso includes second means for protecting the free layer. The secondmeans is disposed on top of the first means. The first means and thesecond means are included in a spin-transfer torque magnetoresistiverandom access memory (STT-MRAM) magnetic tunnel junction (MTJ) device.

Particular advantages provided by at least one of the disclosedembodiments include an ability to protect a free layer of aspin-transfer torque magnetoresistive random access memory (STT-MRAM)magnetic tunnel junction (MTJ) device during etching. Other aspects,advantages, and features of the present disclosure will become apparentafter review of the entire application, including the followingsections: Brief Description of the Drawings, Detailed Description, andthe Claims.

IV. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram to illustrate a particular embodiment of aspin-transfer torque magnetoresistive random access memory (STT-MRAM)magnetic tunnel junction (MTJ) device with a magnetic etch stop layer toreduce degradation of a free layer;

FIG. 2A is a diagram illustrating a particular stage of forming theSTT-MRAM MTJ device of FIG. 1;

FIG. 2B is a diagram illustrating another particular stage of formingthe STT-MRAM MTJ device of FIG. 1;

FIG. 2C is a diagram illustrating another particular stage of formingthe STT-MRAM MTJ device of FIG. 1;

FIG. 2D is a diagram illustrating another particular stage of formingthe STT-MRAM MTJ device of FIG. 1;

FIG. 3 depicts a flowchart to illustrate a particular embodiment of amethod of forming a STT-MRAM MTJ device with a magnetic etch stop layerto reduce degradation of a free layer;

FIG. 4 depicts a flowchart to illustrate another particular embodimentof a method of forming a STT-MRAM MTJ device with a magnetic etch stoplayer to reduce degradation of a free layer

FIG. 5 is a block diagram of a wireless device that includes a STT-MRAMMTJ device with a magnetic etch stop layer; and

FIG. 6 is a data flow diagram of a particular illustrative embodiment ofa manufacturing process to manufacture electronic devices that include aSTT-MRAM MTJ device with a magnetic etch stop layer that reducesdegradation of a free layer.

V. DETAILED DESCRIPTION

Referring to FIG. 1, a particular embodiment of a spin-transfer torquemagnetoresistive random access memory (STT-MRAM) magnetic tunneljunction (MTJ) device 100 with a magnetic etch stop layer formed toreduce degradation of a free layer is shown.

The STT-MRAM MTJ device 100 includes one or more pinned layers 102, atunneling barrier layer 104, a free layer 106, a capping layer 108, amagnetic etch stop layer 110, and a top electrode 112. In a particularembodiment, the STT-MRAM MTJ device 100 may be a perpendicular MTJdevice. For example, the magnetic moment of the free layer 106 and themagnetic moment of at least one of the pinned layers 102 may beperpendicular to the plane of the free layer 106.

The one or more pinned layers 102 may include a reference layer (e.g., afixed layer) and a pinned layer that have magnetic domains oriented inthe same direction. A magnetic domain of the free layer 106 may beprogrammable via a write current to indicate a state of the STT-MRAM MTJdevice 100. For example, if the magnetization of the free layer 106 andthe magnetization of the reference layer have the same orientation, theSTT-MRAM MTJ device 100 may represent a data value having a firstlogical state (e.g., a logical “0”). Alternatively, if the magneticdomain of the free layer 106 and the magnetic domain of the referencelayer have opposite orientations, the STT-MRAM MTJ device 100 mayrepresent a data value having a second logical state (e.g., a logical“1”). In a particular embodiment, the one or more pinned layers 102 maybe deposited on top of a bottom electrode (not shown).

In other embodiments, the one or more pinned layers 102 may also includeone or more seed layers, one or more buffer layers, one or more strayfield balance layers, one or more connection layers, one or moreperformance enhancement layers (e.g., synthetic pinned layers), or anycombination thereof.

The tunneling barrier layer 104 may be deposited between the pinnedlayers 102 and the free layer 106. The tunneling barrier layer 104 maybe an insulating barrier layer having a thickness that enables electronsto tunnel between the free layer 106 and the pinned layers 102 if a biasvoltage is applied across the free layer 106 and the pinned layers 102.The tunneling barrier layer 104 may be comprised of Magnesium Oxide(MgO). In alternative embodiments, the tunneling barrier layer 104 maybe comprised of Aluminum Oxide (Al₂O₃), Zirconium Dioxide (ZrO₂),Zirconium Aluminum Oxide (ZrAlO_(x)), Aluminum Nitride (AlN), AluminumOxynitride (AlON_(x)), Gallium Oxide (Ga₂O₃), or Europium Sulfide (EuS).

The free layer 106 may be a ferromagnetic layer that carries a magneticmoment having a changeable orientation. For example, the magnetic moment(e.g., the magnetic domain) of the free layer 106 may be programmablevia a write current (e.g., a switching current). A direction of themagnetic moment of the free layer 106 relative to a direction of a fixedmagnetic moment carried by the reference layer in the pinned layers 102determines a data value represented by the STT-MRAM MTJ device 100, asexplained above. Thus, if the STT-MRAM MTJ device 100 is a perpendicularMTJ device, the free layer 106 may have a perpendicular magneticanisotropy. That is, the data value of the STT-MRAM MTJ device 100 is“directionally dependent” on the orientation of the magnetic moment ofthe free layer 106. The free layer 106 may be comprised of Cobalt IronBoron (CoFeB), Cobalt Nickel (CoNi), or other alloys of materials suchas CoFeB—Ta, Co/Pt, etc., and may have a thickness between approximately10 Angstroms and 30 Angstroms. In another particular embodiment, thefree layer 106 may be a multi-layer stack of CoFeB/Ta/CoFeB orCoFeB/Co/Ni, etc.

The capping layer 108 may be deposited on top of the free layer 106. Thecapping layer 108 may be comprised of Magnesium Oxide (MgO). The cappinglayer 108 may be configured to protect the free layer 106 duringetching. For example, a hard mask (not shown) may be placed on the topelectrode 112 and the STT-MRAM MTJ device 100 may undergo an etchingprocess such that the length of each layer 102-112 is etched to beapproximately equal to the length of the hard mask. During the etchingprocess, the capping layer 108 may protect magnetic properties of thefree layer 106. For example, the capping layer 108 may stabilize (orincrease) the perpendicular magnetic anisotropy of the free layer 106during high annealing temperatures associated with an etching process(e.g., a reactive ion etching process). Although the capping layer 108is depicted as being comprised of Magnesium Oxide (MgO), in otherembodiments, the capping layer 108 may be comprised of Aluminum Oxide(Al₂O₃) or Hafnium oxide (or other oxide materials such as oxidizedCoFeB, Fe, Ta, etc.).

The magnetic etch stop layer 110 may be deposited on top of the cappinglayer 108. The magnetic etch stop layer 110 may be comprised of CobaltIron Boron (CoFeB). The magnetic etch stop layer 110 may also beconfigured to protect the free layer 106 during etching. For example,when the STT-MRAM MTJ device 100 undergoes the etching process, themagnetic etch stop layer 110 may provide an additional layer ofprotection along with the capping layer 108 to protect the magneticproperties of the free layer 106. For example, the magnetic etch stoplayer 110 may stabilize the perpendicular magnetic anisotropy of thefree layer 106, oxygen distribution, and inter-diffusion during highannealing temperatures associated with an etching process. Although themagnetic etch stop layer 110 is depicted as being comprised of CobaltIron Boron (CoFeB), in other embodiments, the magnetic etch stop layer110 may be comprised of Iron (Fe), Cobalt (Co), Nickel (Ni), Iron Boron(FeB), an alloy thereof, any combination thereof.

In a first embodiment, the magnetic etch stop layer 110 may besufficiently thin as to operate as a “magnetically dead” layer. Forexample, a thickness of the magnetic etch stop layer 110 may cause themagnetic etch stop layer 110 to be substantially magnetically inert. Asa non-limiting illustrative example, the thickness of the magnetic etchstop layer 110 may be approximately 5 Angstroms or less such that themagnetic etch stop layer 110 is substantially magnetically inert. Whenthe magnetic etch stop layer 110 is magnetically inert, the magneticcontribution of the magnetic etch stop layer 110 to the STT-MRAM MTJdevice 100 may be significantly reduced (or may be non-existent). Forexample, using a “thin” Cobalt Iron Boron (CoFeB) layer on top of aMagnesium Oxide (MgO) capping layer may enhance performance of theSTT-MRAM MTJ device 100 by aiding in the formation of high perpendicularmagnetic anisotropy in the free layer while protecting the free layer106 during reactive ion etching (e.g., reducing atomic inter-diffusionprocesses).

In a second embodiment, the thickness of the magnetic etch stop layer110 may cause the magnetic etch stop layer 110 to introduce in-planeanisotropy (e.g., exhibit magnetic moments) to the STT-MRAM MTJ device100. As a non-limiting example, the thickness of the magnetic etch stoplayer 110 may be between approximately 10 Angstroms and 30 Angstroms.The in-plane anisotropy (as opposed to a perpendicular anisotropy havinga magnetic moment oriented out of the plane (e.g., vertically) of theSTT-MRAM MTJ device 100) may reduce the switching current density (orenergy) needed to operate the STT-MRAM MTJ device 100 without degradingtunnel magneto-resistance (TMR) and thermal barrier of the STT-MRAM MTJdevice 100. For example, the magnetic etch stop layer 110 may be“weakly” coupled to the free layer 106 by ferromagnetic coupling. Thefree layer 106 may have a perpendicular anisotropy (e.g., a magneticmoment oriented in a vertical direction) and the magnetic etch stoplayer 110 may have the in-plane anisotropy (e.g., a magnetic momentoriented in a horizontal direction). Due to the in-plane anisotropy,spin polarized electrons may be more effective at inducing a torque ofthe free layer 106, which may reduce the amount of switching currentneeded to change the orientation of the magnetic moment in the freelayer 106. Reducing the amount of switching current needed to change theorientation of the magnetic moment may reduce an amount of energy neededto program the STT-MRAM MTJ device 100.

The top electrode 112 may be deposited on top of the magnetic etch stoplayer 110. A write current (e.g., the switching current) or a readcurrent may be provided to the STT-MRAM MTJ device 100 via the topelectrode 112. For example, the top electrode 112 may function as aninterface to program a data value to the STT-MRAM MTJ device 100 or toread a data value from the STT-MRAM MTJ device 100.

The STT-MRAM MTJ device 100 of FIG. 1 may provide etch-stop protectionto the free layer 106 during an MTJ etching process. For example, themagnetic etch stop layer 110 may function as an etch-stop protectionlayer to the free layer 106 to stabilize the perpendicular magneticanisotropy of the free layer 106 during high annealing temperaturesassociated with the etching process. To illustrate, the magnetic etchstop layer 110 may protect the magnetic properties of the free layer 106during the etching process based on the chemical composition of themagnetic etch stop layer 110 and the capping layer 108 (e.g., a CobaltIron Boron (CoFeB) layer on top of Magnesium Oxide (MgO) capping) whenthe magnetic etch stop layer 110 is approximately 5 Angstroms thick orless. The magnetic etch stop layer 110 may also reduce the switchingcurrent of the STT-MRAM MTJ device 100 without degrading TMR and/or thethermal barrier when the magnetic etch stop layer 110 has a thicknessbetween 10 Angstroms and 30 Angstroms.

Referring to FIG. 2A, a particular stage 202 of forming the STT-MRAM MTJdevice 100 of FIG. 1 is shown. The pinned layers 102, the tunnelingbarrier layer 104, the free layer 106, and the capping layer 108 may beformed within a chamber using physical vapor deposition (PVD) sputteringtechniques. According to the stage 202 of FIG. 2A, the magnetic etchstop layer 110 is deposited on top of the capping layer 108 in thechamber using PVD sputtering techniques.

Referring to FIG. 2B, another particular stage 204 of forming theSTT-MRAM MTJ device 100 of FIG. 1 is shown. According to the stage 204of FIG. 2B, the top electrode 112 is deposited on top of the magneticetch stop layer 110 in the chamber using PVD sputtering techniques.

Referring to FIG. 2C, another particular stage 206 of forming theSTT-MRAM MTJ device 100 of FIG. 1 is shown. According to the stage 206of FIG. 2C, the layers 102-112 are patterned using lithography processes(e.g., electronic beam lithography and/or optical lithography). A hardmask 114 is also placed on the top electrode 112.

Referring to FIG. 2D, another particular stage 208 of forming theSTT-MRAM MTJ device 100 of FIG. 1 is shown. According to the stage 208of FIG. 2D, the layers 102-114 undergo a reactive ion etching (RIE)process. For example, the portions of the layers 102-114 that are notunderneath the hard mask 114 are etched away during the RIE process suchthat the length of each layer 102-114 is etched to be approximatelyequal to the length of the hard mask 114. The magnetic etch stop layer110 (in addition to the capping layer 108) may protect magneticproperties of the free layer 106 during the RIE process. For example,the magnetic etch stop layer 110 may stabilize the perpendicularmagnetic anisotropy of the free layer 106, oxygen distribution, andinter-diffusion to withstand high annealing temperatures associated withthe RIE process. After the RIE process is complete, the hard mask 114may be removed to create the STT-MRAM MTJ device 100 of FIG. 1.

Referring to FIG. 3, a flowchart to illustrate a particular embodimentof a method 300 of forming a STT-MRAM MTJ device with a magnetic etchstop layer that is formed to reduce degradation of a free layer isshown. The method 300 may be performed by manufacturing equipment, asdescribed with respect to FIG. 6. The method 300 may be used tofabricate the STT-MRAM MTJ device 100 of FIG. 1.

The method 300 may include depositing a capping layer on top of a freelayer of the STT-MRAM MTJ device, at 302. For example, referring to FIG.2A, the capping layer 108 (e.g., the Magnesium Oxide (MgO) cappinglayer) may be deposited on top of the free layer 106 in the chamberusing PVD sputtering techniques.

A magnetic etch stop layer may be deposited on top of the capping layer,at 304. For example, referring to FIG. 2A, the magnetic etch stop layer110 (e.g., the Cobalt Iron Boron magnetic etch stop layer) may bedeposited on top of the capping layer 108 in the chamber using PVDsputtering techniques.

In a particular embodiment, the method 300 may also include depositingthe top electrode 112 on top of the magnetic etch stop layer 110 in thechamber using the PVD sputtering techniques as illustrated in FIG. 2B.The method 300 may also include patterning the layers 102-112 usinglithography processes and placing the hard mask 114 on the top electrode114 as illustrated in FIG. 2C. The method 300 may also includeperforming the RIE process on the layers 102-114 as illustrated in FIG.2D. For example, the portions of the layers 102-114 that are notunderneath the hard mask 114 are etched away during the RIE process suchthat the length of each layer 102-114 is etched to be approximatelyequal to the length of the hard mask 114.

The method 300 of FIG. 3 may provide etch-stop protection to the freelayer 106 during the RIE process. For example, the magnetic etch stoplayer 110 may function as an etch-stop protection layer to the freelayer 106 to stabilize the perpendicular magnetic anisotropy of the freelayer 106 during high annealing temperatures associated with the etchingprocess. To illustrate, the magnetic etch stop layer 110 may protect themagnetic properties of the free layer 106 during the etching processbased on the chemical composition of the magnetic etch stop layer 110and the capping layer 108 (e.g., a Cobalt Iron Boron (CoFeB) layer ontop of a Magnesium Oxide (MgO) capping layer) when the magnetic etchstop layer 110 is approximately 5 Angstroms thick or less. The magneticetch stop layer 110 may also reduce the switching current of theSTT-MRAM MTJ device 100 without degrading TMR and/or the thermal barrierwhen the magnetic etch stop layer 110 has a thickness between 10Angstroms and 30 Angstroms.

Referring to FIG. 4, a flowchart to illustrate another particularembodiment of a method 400 of forming a STT-MRAM MTJ device with amagnetic etch stop layer that is formed to reduce degradation of a freelayer is shown. The method 400 may be performed by manufacturingequipment, as described with respect to FIG. 6. The method 300 may beused to fabricate the STT-MRAM MTJ device 100 of FIG. 1.

The method 400 may include depositing one or more pinned layers, atunnel barrier layer, a free layer, and a capping layer into a chamber,at 402. For example, referring to FIG. 1, the pinned layers 102, thetunneling barrier layer 104, the free layer 106, and the capping layer108 may be deposited into a chamber using PVD sputtering techniques.

A decision whether to improve (e.g., “optimize”) perpendicular magneticanisotropy or whether to reduce switching energy may be determined, at404. In response to a decision to improve perpendicular magneticanisotropy, a relatively thin magnetic etch stop layer may be depositedon top of the capping layer, at 406. For example, a thickness of themagnetic etch stop layer 110 may cause the magnetic etch stop layer 110to be substantially magnetically inert. As a non-limiting illustrativeexample, the thickness of the magnetic etch stop layer 110 may beapproximately 5 Angstroms or less such that the magnetic etch stop layer110 is substantially magnetically inert. When the magnetic etch stoplayer 110 is substantially magnetically inert, the magnetic contributionof the magnetic etch stop layer 110 to the STT-MRAM MTJ device 100 maybe significantly reduced (or may be non-existent). For example, using a“thin” Cobalt Iron Boron (CoFeB) layer on top of a Magnesium Oxide (MgO)capping layer may enhance performance of the STT-MRAM MTJ device 100 byaiding in the formation of high perpendicular magnetic anisotropy in thefree layer while protecting the free layer 106 during reactive ionetching (e.g., reducing atomic inter-diffusion processes).

In response to a decision to reduce switching energy, a relatively thickmagnetic etch stop layer may be deposited on top of the capping layer,at 408. For example, the thickness of the magnetic etch stop layer 110may cause the magnetic etch stop layer 110 to introduce in-planeanisotropy (e.g., exhibit magnetic moments) to the STT-MRAM MTJ device100. As a non-limiting example, the thickness of the magnetic etch stoplayer 110 may be between approximately 10 Angstroms and 30 Angstroms.The in-plane anisotropy (as opposed to a perpendicular anisotropy havinga magnetic moment oriented out of the plane (e.g., vertically) of theSTT-MRAM MTJ device 100) may reduce the switching current density (orenergy) needed to operate the STT-MRAM MTJ device 100 without degradingtunnel magneto-resistance (TMR) and a thermal barrier of the STT-MRAMMTJ device 100. For example, the magnetic etch stop layer 110 may be“weakly” coupled to the free layer 106 by ferromagnetic coupling. Thefree layer 106 may have a perpendicular anisotropy (e.g., a magneticmoment oriented in a vertical direction) and the magnetic etch stoplayer 110 may have the in-plane anisotropy (e.g., a magnetic momentoriented in a horizontal direction). Due to the in-plane anisotropy,spin polarized electrons may be more effective at inducing a torque ofthe free layer 106, which may reduce the amount of switching currentneeded to change the orientation of the magnetic moment in the freelayer 106.

Etching and other processes may be performed, at 410. For example, thetop electrode 112 may be deposited on top of the magnetic etch stoplayer 110, the layers 102-112 may be patterned using lithographyprocesses (e.g., electronic beam lithography and/or opticallithography), and the hard mask 114 may be placed on the top electrode112. Additionally, the layers 102-114 may undergo a reactive ion etching(RIE) process. For example, the portions of the layers 102-114 that arenot underneath the hard mask 114 may be etched away during the RIEprocess such that the length of each layer 102-114 is etched to beapproximately equal to the length of the hard mask 114. The magneticetch stop layer 110 (in addition to the capping layer 108) may protectmagnetic properties of the free layer 106 during the RIE process. Forexample, the magnetic etch stop layer 110 may stabilize theperpendicular magnetic anisotropy of the free layer 106, oxygendistribution, and inter-diffusion to withstand high annealingtemperatures associated with the RIE process. After the RIE process iscomplete, the hard mask 114 may be removed to create the STT-MRAM MTJdevice 100 of FIG. 1.

The method 400 of FIG. 4 may provide etch-stop protection to the freelayer 106 during the RIE process. For example, the magnetic etch stoplayer 110 may function as an etch-stop protection layer to the freelayer 106 to stabilize the perpendicular magnetic anisotropy of the freelayer 106 during high annealing temperatures associated with the etchingprocess. To illustrate, the magnetic etch stop layer 110 may protect themagnetic properties of the free layer 106 during the etching processbased on the chemical composition of the magnetic etch stop layer 110and the capping layer 108 (e.g., a Cobalt Iron Boron (CoFeB) layer ontop of a Magnesium Oxide (MgO) capping layer) when the magnetic etchstop layer 110 is approximately 5 Angstroms thick or less. The magneticetch stop layer 110 may also reduce the switching current of theSTT-MRAM MTJ device 100 without degrading TMR and/or the thermal barrierwhen the magnetic etch stop layer 110 has a thickness between 10Angstroms and 30 Angstroms.

Referring to FIG. 5, a block diagram of a particular illustrativeembodiment of a wireless communication device is depicted and generallydesignated 500. The device 500 includes a processor 510 (e.g., a centralprocessing unit (CPU) and a digital signal processor (DSP), etc.)coupled to a memory 532. The memory 532 may include instructions 560executable by the processor 510.

The memory 532 may be a memory device, such as a random access memory(RAM), a magnetoresistive random access memory (MRAM), a STT-MRAM device(e.g., the STT-MRAM MTJ device 100 of FIG. 1), a flash memory, aread-only memory (ROM), a programmable read-only memory (PROM), anerasable programmable read-only memory (EPROM), an electrically erasableprogrammable read-only memory (EEPROM), registers, a hard disk, aremovable disk, or a compact disc read-only memory (CD-ROM). A memorydevice 580 may also be coupled to the processor 510. The memory device580 may include one or more STT-MRAM MTJ devices. For example, thememory device 580 may include the STT-MRAM MTJ device 100 of FIG. 1.

FIG. 5 also shows a display controller 526 that is coupled to theprocessor 510 and to a display 528. An encoder/decoder (CODEC) 534 maybe coupled to the processor 510, as shown. A speaker 536 and amicrophone 538 can be coupled to the CODEC 534. FIG. 5 also shows awireless controller 540 coupled to the processor 510 and to an antenna542. In a particular embodiment, the processor 510, the displaycontroller 526, the memory 532, the CODEC 534, and the wirelesscontroller 540 are included in a system-in-package or system-on-chipdevice (e.g., a mobile station modem (MSM)) 522. In a particularembodiment, an input device 530, such as a touchscreen and/or keypad,and a power supply 544 are coupled to the system-on-chip device 522.Moreover, in a particular embodiment, as illustrated in FIG. 5, thedisplay 528, the input device 530, the speaker 536, the microphone 538,the antenna 542, and the power supply 544 are external to thesystem-on-chip device 522. However, each of the display 528, the inputdevice 530, the speaker 536, the microphone 538, the antenna 542, andthe power supply 544 can be coupled to a component of the system-on-chipdevice 522, such as an interface or a controller.

In conjunction with the described embodiments, an apparatus includesfirst means for protecting a free layer disposed on top of the freelayer. For example, the first means for protecting may include thecapping layer 108 of FIG. 1 (e.g., a Magnesium Oxide (MgO) cappinglayer), one or more other capping layers, or any combination thereof.During an etching process, the capping layer 108 may protect magneticproperties of the free layer 106 of FIG. 1. For example, the cappinglayer 108 may stabilize the perpendicular magnetic anisotropy of thefree layer 106 during high annealing temperatures associated with theetching process (e.g., a reactive ion etching process).

The apparatus may also include second means for protecting the freelayer. The second means is disposed on top of the first means. Forexample, the second means for protecting may include the magnetic etchstop layer 110 of FIG. 1 (e.g., the Cobalt Iron Boron (CoFeB) magneticetch stop layer), one or more other magnetic etch stop layers, or anycombination thereof. The first means for protecting and the second meansfor protecting may be included in a STT-MRAM MTJ device. During anetching process, the magnetic etch stop layer 110 may protect magneticproperties of the free layer 106 of FIG. 1. For example, the magneticetch stop layer 110 may stabilize the perpendicular magnetic anisotropyof the free layer 106 during high annealing temperatures associated withthe etching process (e.g., a reactive ion etching process).

The foregoing disclosed devices and functionalities may be designed andconfigured into computer files (e.g. RTL, GDSII, GERBER, etc.) stored oncomputer readable media. Some or all such files may be provided tofabrication handlers who fabricate devices based on such files.Resulting products include semiconductor wafers that are then cut intosemiconductor die and packaged into a semiconductor chip. The chips arethen employed in devices, such as a communications device (e.g., amobile phone), a tablet, a laptop, a personal digital assistant (PDA), aset top box, a music player, a video player, an entertainment unit, anavigation device, a fixed location data unit, or a computer. FIG. 6depicts a particular illustrative embodiment of an electronic devicemanufacturing process 600.

Physical device information 602 is received at the manufacturing process600, such as at a research computer 606. The physical device information602 may include design information representing at least one physicalproperty of a semiconductor device, such as the STT-MRAM MTJ device 100of FIG. 1. For example, the physical device information 602 may includephysical parameters, material characteristics, and structure informationthat is entered via a user interface 604 coupled to the researchcomputer 606. The research computer 606 includes a processor 608, suchas one or more processing cores, coupled to a computer readable mediumsuch as a memory 610. The memory 610 may store computer readableinstructions that are executable to cause the processor 608 to transformthe physical device information 602 to comply with a file format and togenerate a library file 612.

In a particular embodiment, the library file 612 includes at least onedata file including the transformed design information. For example, thelibrary file 612 may include a library of semiconductor devicesincluding the STT-MRAM MTJ device 100 of FIG. 1, that is provided foruse with an electronic design automation (EDA) tool 620.

The library file 612 may be used in conjunction with the EDA tool 620 ata design computer 614 including a processor 616, such as one or moreprocessing cores, coupled to a memory 618. The EDA tool 620 may bestored as processor executable instructions at the memory 618 to enablea user of the design computer 614 to design a device, such as theSTT-MRAM MTJ device 100 of FIG. 1, of the library file 612. For example,a user of the design computer 614 may enter circuit design information622 via a user interface 624 coupled to the design computer 614. Thecircuit design information 622 may include design informationrepresenting at least one physical property of a semiconductor device,such as the STT-MRAM MTJ device 100 of FIG. 1. To illustrate, thecircuit design property may include identification of particularcircuits and relationships to other elements in a circuit design,positioning information, feature size information, interconnectioninformation, or other information representing a physical property of asemiconductor device.

The design computer 614 may be configured to transform the designinformation, including the circuit design information 622, to complywith a file format. To illustrate, the file formation may include adatabase binary file format representing planar geometric shapes, textlabels, and other information about a circuit layout in a hierarchicalformat, such as a Graphic Data System (GDSII) file format. The designcomputer 614 may be configured to generate a data file including thetransformed design information, such as a GDSII file 626 that includesinformation describing a device, such as the STT-MRAM MTJ device 100 ofFIG. 1. To illustrate, the data file may include informationcorresponding to a system-on-chip (SOC) that includes the STT-MRAM MTJdevice 100 of FIG. 1, and that also includes additional electroniccircuits and components within the SOC.

The GDSII file 626 may be received at a fabrication process 628 tomanufacture a semiconductor device, such as the STT-MRAM MTJ device 100of FIG. 1, according to transformed information in the GDSII file 626.For example, a device manufacture process may include providing theGDSII file 626 to a mask manufacturer 630 to create one or more masks,such as masks to be used with photolithography processing, illustratedas a representative mask 632. The mask 632 may be used during thefabrication process to generate one or more wafers 633, which may betested and separated into dies, such as a representative die 636. Thedie 636 includes a circuit including the STT-MRAM MTJ device 100 of FIG.1.

In a particular embodiment, the fabrication process 628 may be initiatedby or controlled by a processor 634. The processor 634 may access amemory 635 that includes executable instructions 637, such ascomputer-readable instructions or processor-readable instructions. Theexecutable instructions may include one or more instructions that areexecutable by a computer, such as the processor 634. The fabricationprocess 628 may be implemented by a fabrication system that is fullyautomated or partially automated. For example, the fabrication process628 may be automated and may perform processing steps according to aschedule. The fabrication system may include fabrication equipment(e.g., processing tools) to perform one or more operations to form anelectronic device.

The fabrication system may have a distributed architecture (e.g., ahierarchy). For example, the fabrication system may include one or moreprocessors, such as the processor 634, one or more memories, such as thememory 635, and/or controllers that are distributed according to thedistributed architecture. The distributed architecture may include ahigh-level processor that controls and/or initiates operations of one ormore low-level systems. For example, a high-level portion of thefabrication process 628 may include one or more processors, such as theprocessor 634, and the low-level systems may each include or may becontrolled by one or more corresponding controllers. A particularcontroller of a particular low-level system may receive one or moreinstructions (e.g., commands) from a high-level system, may issuesub-commands to subordinate modules or process tools, and maycommunicate status data back to the high-level system. Each of the oneor more low-level systems may be associated with one or morecorresponding pieces of fabrication equipment (e.g., processing tools).In a particular embodiment, the fabrication system may include multipleprocessors that are distributed in the fabrication system. For example,a controller of a low-level system component of the fabrication systemmay include a processor, such as the processor 634.

Alternatively, the processor 634 may be a part of a high-level system,subsystem, or component of the fabrication system. In anotherembodiment, the processor 634 includes distributed processing at variouslevels and components of a fabrication system.

The die 636 may be provided to a packaging process 638 where the die 636is incorporated into a representative package 640. For example, thepackage 640 may include the single die 636 or multiple dies, such as asystem-in-package (SiP) arrangement. The package 640 may be configuredto conform to one or more standards or specifications, such as JointElectron Device Engineering Council (JEDEC) standards.

Information regarding the package 640 may be distributed to variousproduct designers, such as via a component library stored at a computer646. The computer 646 may include a processor 648, such as one or moreprocessing cores, coupled to a memory 650. A printed circuit board (PCB)tool may be stored as processor executable instructions at the memory650 to process PCB design information 642 received from a user of thecomputer 646 via a user interface 644. The PCB design information 642may include physical positioning information of a packaged semiconductordevice on a circuit board, the packaged semiconductor devicecorresponding to the package 640 including a device, such as theSTT-MRAM MTJ device 100 of FIG. 1.

The computer 646 may be configured to transform the PCB designinformation 642 to generate a data file, such as a GERBER file 652 withdata that includes physical positioning information of a packagedsemiconductor device on a circuit board, as well as layout of electricalconnections such as traces and vias, where the packaged semiconductordevice corresponds to the package 640 including the STT-MRAM MTJ device100 of FIG. 1. In other embodiments, the data file generated by thetransformed PCB design information may have a format other than a GERBERformat.

The GERBER file 652 may be received at a board assembly process 654 andused to create PCBs, such as a representative PCB 656, manufactured inaccordance with the design information stored within the GERBER file652. For example, the GERBER file 652 may be uploaded to one or moremachines to perform various steps of a PCB production process. The PCB656 may be populated with electronic components including the package640 to form a representative printed circuit assembly (PCA) 658.

The PCA 658 may be received at a product manufacture process 660 andintegrated into one or more electronic devices, such as a firstrepresentative electronic device 662 and a second representativeelectronic device 664. As an illustrative, non-limiting example, thefirst representative electronic device 662, the second representativeelectronic device 664, or both, may be selected from the group of acommunications device (e.g., a mobile phone), a tablet, a laptop, apersonal digital assistant (PDA), a set top box, a music player, a videoplayer, an entertainment unit, a navigation device, a fixed locationdata unit, and a computer, into which the STT-MRAM MTJ device 100 ofFIG. 1 is integrated. As another illustrative, non-limiting example, oneor more of the electronic devices 662 and 664 may be remote units suchas mobile phones, hand-held personal communication systems (PCS) units,portable data units such as personal data assistants, global positioningsystem (GPS) enabled devices, navigation devices, fixed location dataunits such as meter reading equipment, or any other device that storesor retrieves data or computer instructions, or any combination thereof.In addition to remote units according to teachings of the disclosure,embodiments of the disclosure may be suitably employed in any devicewhich includes active integrated circuitry including memory and on-chipcircuitry.

A device, such as the STT-MRAM MTJ device 100 of FIG. 1, may befabricated, processed, and incorporated into an electronic device, asdescribed in the illustrative process 600. For example, the STT-MRAM MTJdevice 100 of FIG. 1 may be integrated into a die in an electronicdevice. The electronic device may include a communications device, atablet, a laptop, a set top box, a music player, a video player, anentertainment unit, a navigation device, a personal digital assistant(PDA), a fixed location data unit, or a computer. One or more aspects ofthe embodiments disclosed with respect to FIGS. 1-4 may be included atvarious processing stages, such as within the library file 612, theGDSII file 626, and the GERBER file 652, as well as stored at the memory610 of the research computer 606, the memory 618 of the design computer614, the memory 650 of the computer 646, the memory of one or more othercomputers or processors (not shown) used at the various stages, such asat the board assembly process 654, and also incorporated into one ormore other physical embodiments such as the mask 632, the die 636, thepackage 640, the PCA 658, other products such as prototype circuits ordevices (not shown), or any combination thereof. Although variousrepresentative stages of production from a physical device design to afinal product are depicted, in other embodiments fewer stages may beused or additional stages may be included. Similarly, the process 600may be performed by a single entity or by one or more entitiesperforming various stages of the process 600.

Those of skill would further appreciate that the various illustrativelogical blocks, configurations, modules, circuits, and algorithm stepsdescribed in connection with the embodiments disclosed herein may beimplemented as electronic hardware, computer software executed by aprocessing device such as a hardware processor, or combinations of both.Various illustrative components, blocks, configurations, modules,circuits, and steps have been described above generally in terms oftheir functionality. Whether such functionality is implemented ashardware or executable software depends upon the particular applicationand design constraints imposed on the overall system. Skilled artisansmay implement the described functionality in varying ways for eachparticular application, but such implementation decisions should not beinterpreted as causing a departure from the scope of the presentdisclosure.

The steps of a method or algorithm described in connection with theembodiments disclosed herein may be embodied directly in hardware, in asoftware module executed by a processor, or in a combination of the two.A software module may reside in a memory device, such as random accessmemory (RAM), magnetoresistive random access memory (MRAM), spin-torquetransfer MRAM (STT-MRAM), flash memory, read-only memory (ROM),programmable read-only memory (PROM), erasable programmable read-onlymemory (EPROM), electrically erasable programmable read-only memory(EEPROM), registers, hard disk, a removable disk, or a compact discread-only memory (CD-ROM). An exemplary memory device is coupled to theprocessor such that the processor can read information from, and writeinformation to, the memory device. In the alternative, the memory devicemay be integral to the processor. The processor and the storage mediummay reside in an application-specific integrated circuit (ASIC). TheASIC may reside in a computing device or a user terminal. In thealternative, the processor and the storage medium may reside as discretecomponents in a computing device or a user terminal.

The previous description of the disclosed embodiments is provided toenable a person skilled in the art to make or use the disclosedembodiments. Various modifications to these embodiments will be readilyapparent to those skilled in the art, and the principles defined hereinmay be applied to other embodiments without departing from the scope ofthe disclosure. Thus, the present disclosure is not intended to belimited to the embodiments shown herein but is to be accorded the widestscope possible consistent with the principles and novel features asdefined by the following claims.

What is claimed is:
 1. An apparatus comprising: a capping layer disposedon top of a free layer; a magnetic layer disposed on top of the cappinglayer; and an electrode layer disposed between the magnetic layer and ahard mask layer, wherein the capping layer and the magnetic layer areincluded in a spin-transfer torque magnetoresistive random access memory(STT-MRAM) magnetic tunnel junction (MTJ) device.
 2. The apparatus ofclaim 1, wherein the capping layer is comprised of Magnesium Oxide,Aluminum Oxide, Hafnium Oxide, or Tantalum Oxide.
 3. The apparatus ofclaim 1, wherein the magnetic layer is comprised of Cobalt Iron Boron,Cobalt Iron, Iron Boron, Nickel Iron Boron, Nickel Iron Silicon Boron,or Nickel Iron.
 4. The apparatus of claim 1, wherein a thickness of themagnetic layer causes the magnetic etch stop layer to be substantiallymagnetically inert.
 5. The apparatus of claim 4, wherein the thicknessof the magnetic layer is less than 5 Angstroms.
 6. The apparatus ofclaim 4, wherein the thickness of the magnetic layer is approximately 5Angstroms.
 7. The apparatus of claim 1, wherein the STT-MRAIVI MTJdevice is a perpendicular MTJ device.
 8. The apparatus of claim 7,wherein a thickness of the magnetic layer causes the magnetic layer tointroduce in-plane anisotropy to the STT-MRAM MTJ device.
 9. Theapparatus of claim 8, wherein the thickness of the magnetic layer isbetween approximately 10 Angstroms and 30 Angstroms.
 10. An apparatuscomprising: first means for protecting a free layer disposed on top ofthe free layer; second means for protecting the free layer, the secondmeans disposed on top of the first means for protecting, wherein thesecond means comprises a magnetic material; and means for conductingdisposed between the second means and means for masking, wherein thefirst means and the second means are included in a spin-transfer torquemagnetoresistive random access memory (STT-MRAM) magnetic tunneljunction (MTJ) device.
 11. The apparatus of claim 10, wherein the firstmeans for protecting is comprised of Magnesium Oxide, Aluminum Oxide,Hafnium Oxide, or Tantalum Oxide.
 12. The apparatus of claim 10, whereinthe second means for protecting is comprised of Cobalt Iron Boron,Cobalt Iron, Iron Boron, Nickel Iron Boron, Nickel Iron Silicon Boron,or Nickel Iron.
 13. The apparatus of claim 10, wherein a thickness ofthe second means for protecting causes the second means for protectingto be substantially magnetically inert.
 14. The apparatus of claim 13,wherein the thickness of the second means for protecting is less than 5Angstroms.
 15. The apparatus of claim 13, wherein the thickness of thesecond means for protecting is approximately 5 Angstroms.
 16. Theapparatus of claim 10, wherein the STT-MRAIVI MTJ device is aperpendicular MTJ device.
 17. The apparatus of claim 16, wherein athickness of the second means for protecting causes the second means forprotecting to introduce in-plane anisotropy to the STT-MRAM MTJ device.18. The apparatus of claim 17, wherein the thickness of the second meansfor protecting is greater than approximately 10 Angstroms.
 19. Aperpendicular spin-transfer torque magnetoresistive random access memory(STT-MRAM) magnetic tunnel junction (MTJ) device comprising: a MagnesiumOxide (MgO) capping layer disposed on top of a free layer; and a5-Angstrom thick Cobalt Iron Boron (CoFeB) magnetic layer disposed ontop of the MgO capping layer; and an electrode layer disposed betweenthe 5-Angstrom thick Cobalt Iron Boron (CoFeB) magnetic layer and a hardmask layer.
 20. The perpendicular STT-MRAM MTJ device of claim 19,wherein the 5-Angstrom thick CoFeB magnetic layer is substantiallymagnetically inert.
 21. The apparatus of claim 1, wherein the cappinglayer is comprised of Magnesium Oxide.
 22. The apparatus of claim 1,wherein the capping layer is comprised of Aluminum Oxide.
 23. Theapparatus of claim 1, wherein the capping layer is comprised of HafniumOxide.
 24. The apparatus of claim 1, wherein the capping layer iscomprised of Tantalum Oxide.
 25. The apparatus of claim 1, wherein themagnetic layer is comprised of Cobalt Iron Boron.
 26. The apparatus ofclaim 1, wherein the magnetic layer is comprised of Cobalt Iron.
 27. Theapparatus of claim 1, wherein the magnetic layer is comprised of IronBoron.
 28. The apparatus of claim 1, wherein the magnetic layer iscomprised of Nickel Iron Boron.
 29. The apparatus of claim 1, whereinthe magnetic layer is comprised of Nickel Iron Silicon Boron.
 30. Theapparatus of claim 1, wherein the magnetic layer is comprised of NickelIron.